A common method of repairing bone fractures involves the insertion of fracture rods, i.e., intramedullary rods or "nails," fixation pins and the like, into the intermedullary canal of the bone. However, it can be difficult to correctly position the entry point or hole relative to the intermedullary canal and accurate positioning of the entry point is critical to proper intermedullary "nailing."
This problem can perhaps be better understood by reference to FIG. 1 wherein a portion of the pelvis is indicated at P, a long bone is indicated at B and the "soft" bone at the top of the long bone B is indicated at S. The soft bone S must be penetrated in order to provide access to the medullary canal MC to enable placement of an intermedullary rod or "nail" along this canal. In FIG. 1, a conventional reamer R is shown driving a conventional straight drill or associated straight drill pin into the soft bone S to create an entry point for the rod. The entry point for the insertion of the rod is often hidden by muscle and hard to access because of the soft tissue. It will be seen in FIG. 1 that a straight reamer or drill can produce an entry point EP that is substantially offset from the bone axis and the axis of the medullary canal MC so that as the straight drill continues along its path the drill can overshoot the canal and problems can then be created in attempting to insert a straight fracture rod.
As discussed below, in one embodiment of the invention, the guide pin of the invention is used in combination with an entry guide tool. A surgical tool guide and entry hole positioner of interest is disclosed in U.S. Pat. No. 5,642,447 (Myers). In one embodiment, the tool guide disclosed in Myers patent includes a guide sleeve which is curved, rather than straight as in the other embodiments, and is adapted for use with flexible reamers. According to the Myers patent, the reamers can be used without changing sleeves and, in this regard, as stated in the patent, the tips of the flexible reamer are merely enlarged incrementally so as to ream the intramedullary canal to a size large enough to receive the fracture fixation rod (nail).
As is also discussed below, the invention is also concerned with an improved protective retractor device which is useful during reaming operations. Prior art protective retractor devices are also discussed briefly hereinbelow.